Higher alkyl 4-hydroxy-3-ethoxybenzoate and process for making same



UNITED STATES Patented Sept. 1, 1953 Irwin A. Pearl, Appleton, Wis., assignor to The Institute of Paper Chemistry, Appleton, Wis., 21.

OFFICE corporation of Wisconsin No Drawing. Application March 8, 1952, Serial No. 275,689

8 Claims. 1

The present invention relates generally to higher alkyl 4-hydroxy-3-ethoxybenzoates and, more particularly, it relates to therapeutic products which are toxic to various pathogenic organisms and bacteria.

Various compounds have been found which are highly toxic toward the bacteria Bacillus mycoicles. Furthermore, it has been found that the toxicity of such compounds toward this bacteria is indicative of their toxicity toward a great number of pathogenic organisms such as Histoplasma capsulatum, Blastomyccs dermatitis and 000mdioides immitis, and also toward other bacteria such as Brucella abortus, Brucella suis, Staphylococcus aureus, Cornynebacterium diphtheriae, Bacillus anthracis, and alpha and beta streptococu.

An object of the present invention is the provision of new chemical compounds which are toxic to the bacteria Bacillus mycoicles and the provision of novel processes for making these compounds. Another object is to provide more intermediate compounds from which the previously mentioned compounds may be easily made. A particular object of the invention is to provide a new compound which has greater toxicity toward this bacteria than any previously known compounds in this or related classes of compounds.

I have discovered that higher alkyl (eight to ten carbon atoms) 4-hydroxy-3-ethoxybenzoate is highly toxic to the bacteria Bacillus mycoioles and that n-octyl 4-hydroxy-3-ethoxybenzoate shows a greater toxicity to the bacteria Bacillus mycoides than any compound in this or related classes of compounds known heretofore. In the latter connection, the other higher alkyl l-hydroxy-3-ethoxybenzoates and previous y known compounds in this and relatedseries of compounds have been effective against the bacteria Bacillus mycoides only at concentrations ranging from 0.006 per cent to 0.15 per cent but I have found that n-octyl 4-hydroxy-3-ethoxybenzoate is effective against this bacteria at a concentration of less than 0.0006 per cent.

In general, the higher alkyl (eight to ten carbon atoms) l-hydroxy-3-ethoxybenzoate is easily prepared from 4-hydroXy-3-ethoxybenzaldehyde by first preparing a higher alkyl 4-hydroxy-3- ethoxybenzimidate acid salt from 4-hydroxy-3- ethoxybenzaldehyde oxime. The acid salt is then hydrolyzed to produce the higher alkyl 4-hydroxy-S-ethoxybenzoate.

A process of this type is illustrated generally below by the following formulas, wherein R represents an alkyl chain containing eight to ten carbon atoms.

OH OH OH 5 0111 002115 OCzHzs CHO GEN 4-hydroxy- In general, the higher alkyl 4-hydroxy-3-ethoxybenzoates may be prepared in accordance with my novel process by first reacting 4-hydroxy-3- ethoxybenzaldehyde with a neutralized solution of a salt of hydroxylamine such as the hydrochloride, sulfate, or acid sulfate salts, which are readily available articles of commerce. This reaction results in l-hydroxy-3-ethoxybenzaldehyde oxime which is converted to 4-hydroxy-3-ethoxybenzonitrile by dehydration of the oxime by a suitable dehydrating agent such as acetic anhydride. Other dehydrating agents may be used such as propionic anhydride, phosphorous pentoxide, and thionyl chloride.

When acetic anhydride is used to dehydrate the oxime, an intermediate product, 4-acetoxy3- ethoxybenzonitrile, is formed. This intermediate product is then selectively hydrolyzed with an acid to provide the 4i-hydroxy-3-ethoxybenzonitrile.

As before indicated, the benzonitrile is converted to an acid salt of higher alkyl 4-hydroxy-3- ethoxybenzimidate, this being accomplished by reacting the 4-hydroxy-3-ethoxybenzonitrile with a higher alkyl alcohol in the presence of an excess of an anhydrous acid while preventing nitration and demethylation, thereby permitting higher alkyl 4-hydroxy-3-ethoxybenzimidate to be isolated as the acid addition salt.

The anhydrous acid employed is preferably gaseous hydrochloric acid, though other acids, both organic and inorganic may be used, such as sulfuric and toluenesulfonic acids, without causing either nitration of demethylation. A

. sodium hydroxide.

nitrating acid, such as nitric acid, or a demethylating acid, as for example hydroiodic, will result in decreased yields.

The higher alkyl 4-hydroxy-3-ethoxybenzimidate acid salt may be isolated or/may be immediately and easily hydrolyzed, in a neutral or slightly acidic solution, to produce a higher alkyl 4-hydroxy-3-ethoxybenzoate, each of the benzoates being novel compounds of high purity 4 drous ether, the precipitat being white crystals which melt at 155 C.

The n-octyl 4-hydroxy-3-ethoxybenzimidate hydrochloride crystals resulting from the previous 5 .step may,,then-;be hydrolyzed to produce 4-hydroxy-B-ethoxybenzoateibymixing 46 grams of the salt with 250 cc. of water and boiling the mix- :ture under reflux for two hours. This mixture is then extracted with ether and the ether washed which are very efiective against the bacteria:10.'-withgsaturatedisndinm bicarbonate solution. The

Bacillus mycoides.

EXAMPLE .1

Preparation of n-octyl -.4.=hy dr oxy-B- ethoarybenzoate In the preparation of n-octyldehydroxy-3- ethoxybenzoate, 4 hydroxy-B-ethoxybenzeildehyde oxime is first prepared by dissolving .498 grams of 4-hydroxy-3-ethoxybenzaldehyde in a hot (90 0.) solution comprising 144 grams of sodium hydroxide in 1800 cc. of water. To this mixture is added 251 grams of hydro-xyla-rnine hydrochlcrideywhereupon the zcombined mixture is stirred until cool. Upon addition of the hydroxylamine hydrochloride the oxime forms as an oil which solidifies upon cooling of the solution. Ehe resulting solid is filtered, washed with water, and air dried to provide a solidmelting of 102 C. Recrystallization of the solid from high boiling ether gives .white crystals melting at.l02 C.

The needles of 4:hydroxy- 3-ethoxybenzaldehyde oxime are dehydrated by mixing 218 grains of the "oxime with 640 grams of acetic anhydride and ='boiling the mixture under reflux for two hours. Afterrefluxing, the solution is cooled and stirred into 2500 cc. ofrcold C.) water thereby forming a whiteiprecipitate of 4-acetoxy-3- ethoxybenzonitrile. The precipitate is filtered,

washed with water 'and'dried so as to provide a The 4-acetoxy 3-et'hoxybenzonitri1e is then selectively hydrolyzed :to rl-hydroxy-iteethoxy- :benzonitrile by, preparing a mixture of .l56z-grarns .of the-former and-A50 .cc; of concentratedzhydro- -chl0ric acid, .the mixture ;being.--heated to 165 ,C. .and until all .of the :solid. has-idissolved. Ihe

heated-solution is 'cooledzand BOOB-coach cold-.(-l5

Ct) water is added. Thedilute solutionibecomes cloudy and .is neutralized to gpH 4.5 with dilute neutralized solution and ;this:oil solidifies :upon standing. The entire -mixtur.e is then extracted with ether, the ethersolution 'being .dried .and distilled to yield 4-hydroxy-3eethoxybenzonitrile as a light colored solidmeltingat-GS 1C. ..Re-;-

crystallization from high boilingpetroleum:ether yieldswhite needles melting at 66vv C.

The solid benzonitrile is thenconvertedtothe acid salt of n-octyl d-hydroxy-fi-ethoxybenzimidate, this being accomplished by preparing .a mixture of '50 grams of the benzonitrile, 41. grams of n-octyl alcohol, andl50 cc. of.-.anhy.drousethyl ether, cooling the mixture in-an .ice. bath, and bubbling gaseous hydrochloric. acid intothemixture for onehour. :Aftertreatmentwithsthe gas,

the mixture is capped with a (calcium. :chloride tube .andallowed .to. stand at room .temperature for 24. hours.

Upon. standing, a heavy precipitate-separates cut and is recovered: by Tfiltering, theaprecipitate .beingwashed with ether and allowed to .dry in air. The. driedpreipitate .weighsfidgramsend comprises an almost. white. powder whichimelts. at 154-155 10. Thepowdei-iis, purified by. dissolving An oil separates vout ofithe 50 etheris-thendriedand distilled, the residue being distilled under reduced pressure to yield n-oct-yl .ehydmXWBeethoxybenzoate as a colorless oil which iboi'lszat .182? C. at 1.5 mm. The index of 1 5 refraotion of the oil is 11 1.5093. The oil solidi- ..iies onstandingto a crystalline solid having a melting point of'32-33 C.

EXAMPLE II Preparation of n-nong/l 4-hydrory-3-ethory- -..benzimrid te .ltydrochloride n-Nonyl -4-hydroxy-3iethoxybenzimidate .hy- 'droc'hloride is prepared- .by iollowing the procedure set foiith inExampleit for preparing noctyl 4-hydroxy-3-ethoxybenzimidate hydrocliloride 'except that-45 grams of .n -nonyl alcohol isemployed.

, EXAMPLE I III .flrepamtionzofrneno-nyl=i-hydory-3-ethoxybenzoate .40 viE'XAM-PLE :IV

' Preparation of -n-dc cyl 4 hydroxy-3-ethoasy- .bene'imida'te lgydroc'hloride idl'QChlOIi'dfi is,;pre.par ed :in :the same manner as than-octyl -:khydroxye3-sethoxybenzimidate hyo i eci pi 'qp i dzin ExampleL-except that 149 :grams of nedecyhalcohol,is:,used. -,i;his process yields n-decyl i-hydroxy-3-ethoxybenzimidate hydrochloride as a :White powder "which melts at 91 5.5:1'5 6 C etflzoalgybenz0atie "The -n-decyl 4-hydroxy-3-ethoxybenzimidate hydrochloride-ofthe-previous example is selectively hydrolyzed inythe-same manner as the =n-octyl i-hydroxy Seethoxybenzimidate hydro- '60 -ch1oride 'is hydrolyze'd" in -=-Example I to produce n-decy1- :4=hydrcxy-3 ethoxybenzoate. In this process,- a colorless *oil boiling 'at"1-97 C. at 115 mm; is formed; the oil 'hav-ing-- an'index' of refraction of nff lfillo. "The-oil solidifies to a crysta line solid, as in Example L-which'solidmelts at lhus; the h-igheralkyl-4 hydroxy 3 ethoxyzen- =-zoates,-whichare toxic toward Bacillus mycoides, are-easily preparedin-eccordance :with -my invention, this *beingreadilydone fromthe a novel intermediate. products; the acid-salts of higher alkyl 4g-h-ydroxye3rethoxybenzimidate.

The various featuressofcthe.inventionwhich vare-iibelievedrnewaarea setyforth, in the;follo,wing

it in. chloroformaandL precipitatingiit; -withanhy- ,{5 -claims.

I claim:

1. A process for producing an alkyl ester of 4- hydroxy-3-ethoxybenzoic acid in which the alkyl constituent contains from eight to ten carbon atoms comprising the steps of reacting 4-hydroxy-3-ethoxybenzaldehyde with a salt of hydroxylamine, dehydrating the resulting 4-hydroxy-3-ethoxybenza1dehyde oxime to produce l-hydroxy 3 ethoxybenzonitrile, reacting the benzonitrile with an alkyl alcohol containing from eight to ten carbon atoms in the presence of an anhydrous acid and under anhydrous conditions to produce the alkyl ester 4-hydroxy-3-ethoxybenzimidate acid salt, and hydrolyzin'g the acid salt to the 4-hydroxy-3-ethoxyalky1benzoate.

2. The process for producing an alkyl ester of 4-hydroxy-S-ethoxybenzoic acid in which the alkyl constituent contains from eight to ten carbon atoms which comprises the steps of reacting e-hydroxy-3-ethoxybenzonitrile with an alkyl alcohol containing from eight to ten carbon atoms in the presence of anhydrous acid and under anhydrous conditions to produce higher alkyl 4- hydroxy-3-ethoxybenzimidate acid salt, and hydrolyzing the acid salt to produce the 4-hydroxy- 3-ethoxya1ky1benzoate.

3. The process for producing an acid salt of 4- hydroxy-3-ethoxybenzimidate which comprises the steps of reacting 4-hydroxy-3-ethoxybenzonitrile with an alkyl alcohol containing from eight to ten carbon atoms in the presence of an anhydrous acid and under anhydrous conditions while preventing nitration and demethylation.

4. The product n-octyl 4-hydroxy-3-ethoxybenzoate.

5. The benzoate.

6. The benzoate.

'7. A i-hydroxy-3-ethoxyalkylbenzimidate acid salt in which the alkyl constituent contains from eight to ten carbon atoms.

8. An alkyl ester of 4-hydroxy-3-ethoxybenzoic acid, the alkyl constituent of said ester containing from eight to ten carbon atoms.

IRWIN A. PEARL.

product n-nonyl 4-hydroxy-3-ethoxyproduct n-decyl 4-hydroxy-3-ethoxy- No references cited. 

3. THE PROCESS FOR PRODUCING AN ACID SALT OF 4HYDROXY-3-ETHOXYBENZIMIDATE WHICH COMPRISES THE STEPS OF REACTING 4-HYDROXY-3-ETHOXYBENZONITRILE WITH AN ALKYL ALCOHOL CONTAINING FROM EIGHT TO TEN CARBON ATOMS IN THE PRESENCE OF AN ANHYDROUS ACID AND UNDER ANHYDROUS CONDITIONS WHILE PREVENTING NITRATION AND DEMETHYLATION.
 7. A 4-HYDROXY-3-ETHOXYALKYLBENZIMIDATE ACID SALT IN WHICH THE ALKYL CONSTITUENT CONTAINS FROM EIGHT TO TEN CARBON ATOMS. 